Study Underscores Importance of Early Vision Screening

Nearly One Third of Children in Study Had Correctable Refractive Errors

As kids head back to school or start kindergarten, it's the perfect time to make sure they have the best possible vision. A study of more than 10,000 preschoolers gives parents information on vision risks based on ethnicity and other factors and underscores the importance of early vision screenings.

Nearly a third of the preschoolers in the study had refractive errors, slight irregularities in eye shape that affect how well images can focus on the retina. About 4 percent were nearsighted, 21 percent were farsighted and 10 percent had astigmatism. All three of these refractive errors cause blurry vision. African-American kids were more likely to be nearsighted but less likely to be farsighted than Hispanic and non-Hispanic white children. Astigmatism was most likely among Hispanic children followed by African-Americans, and least likely in non-Hispanic white kids.

Also, about 5 percent of the children had amblyopia, known as "lazy eye," and about 2 percent had strabismus, a misalignment condition commonly called "wandering eye."

The study found that even when kids' refractive errors were mild, they were at higher risk of amblyopia and strabismus. These two conditions can occur separately or together, and need to be corrected as early in life as possible, ideally before kindergarten. If not treated, they can result in permanent, lifelong vision loss that can limit job options and enjoyment of life. For instance, either of these disorders can lead to loss of depth perception.

Strabismus is easier for a parent to spot, because one of the child's eyes may turn inward or outward, some or all of the time. In amblyopia, one eye is stronger than the other due to strabismus or other causes, but since the child may appear perfectly normal it can be hard for a parent to detect a problem. This is why preschoolers need to have vision screening by trained health professionals at their doctor's office, clinic or school.

Treatment for amblyopia is often as simple as "patching" the stronger eye for part of the day so that the weaker eye has to work harder, which helps it develop normally. Eyeglasses may be needed if the child also has a refractive error. Strabismus treatment sometimes involves surgery.

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